I would not rebuild until I checked a few other things, if the plug is clean, blowby may not be the issue. Might be simple as a defective PCV, it should allow air out, but the reed valve should not allow it back into the engine.
As for the compression, B&S has refused for many years to publish compression data in their service manuals, unless they started recently. The standard they recomended was to rotate the flywheel backwards against the compression stroke, if it bounced back it has enough to run. Valve stem clearence being a far more common loss of compression and power than rings/cylinder wear in these motors. B&S does not consider an engine to be using excessive oil unless in burns more than 4 oz/hour.
If the engine is running well and the oil in the breather is not enough to cause the plug to foul or engine to miss, I would ignore that in favor of watching for more serious indications like oil consumtion, or quickly fouled plugs.